Noise Source Localization Using a Compact Phased Array: Studies on a Full Scale Wind Turbine in a Wind Farm

2012 ◽  
Vol 36 (5) ◽  
pp. 589-604 ◽  
Author(s):  
Rakesh C. Ramachandran ◽  
Ganesh Raman ◽  
Robert P. Dougherty
Keyword(s):  
Wind Turbine ◽  
Wind Farm ◽  
Microphone Array ◽  
Low Noise ◽  
Full Scale ◽  
Microphone Arrays ◽  
Aerodynamic Noise ◽  
Noise Sources ◽  
Blade Tip ◽  
Primary Focus

Locating the dominant noise sources on a wind turbine is an important problem in designing and developing low noise wind turbines. Previously very large microphone arrays were used to locate these sources. The primary focus of this paper is to show that using a compact and mobile microphone array with advanced beamforming algorithms, the noise sources can be successfully located and quantified. The results from the qualification experiments on the microphone array conducted in laboratory using synthetic noise sources show the differences between the various beamforming algorithms used in this study (both frequency and time domain algorithms). The initial experimental results on a full scale wind turbine reveal that it is indeed possible to locate the noise sources using a compact microphone array by successfully locating the two dominant noise sources on the wind turbine namely, aerodynamic noise near the blade tip and mechanical noise from nacelle.

scholarly journals Research on Aerodynamic Noise Reduction for High-Speed Trains

2016 ◽  
Vol 2016 ◽  
pp. 1-21 ◽  
Author(s):  
Yadong Zhang ◽  
Jiye Zhang ◽  
Tian Li ◽  
Liang Zhang ◽  
Weihua Zhang
Keyword(s):  
Noise Reduction ◽  
High Speed ◽  
Low Noise ◽  
Broadband Noise ◽  
Full Scale ◽  
Noise Model ◽  
Aerodynamic Noise ◽  
High Speed Train ◽  
Detached Eddy Simulation ◽  
Noise Sources

A broadband noise source model based on Lighthill’s acoustic theory was used to perform numerical simulations of the aerodynamic noise sources for a high-speed train. The near-field unsteady flow around a high-speed train was analysed based on a delayed detached-eddy simulation (DDES) using the finite volume method with high-order difference schemes. The far-field aerodynamic noise from a high-speed train was predicted using a computational fluid dynamics (CFD)/Ffowcs Williams-Hawkings (FW-H) acoustic analogy. An analysis of noise reduction methods based on the main noise sources was performed. An aerodynamic noise model for a full-scale high-speed train, including three coaches with six bogies, two inter-coach spacings, two windscreen wipers, and two pantographs, was established. Several low-noise design improvements for the high-speed train were identified, based primarily on the main noise sources; these improvements included the choice of the knuckle-downstream or knuckle-upstream pantograph orientation as well as different pantograph fairing structures, pantograph fairing installation positions, pantograph lifting configurations, inter-coach spacings, and bogie skirt boards. Based on the analysis, we designed a low-noise structure for a full-scale high-speed train with an average sound pressure level (SPL) 3.2 dB(A) lower than that of the original train. Thus, the noise reduction design goal was achieved. In addition, the accuracy of the aerodynamic noise calculation method was demonstrated via experimental wind tunnel tests.

Aerodynamic Noise Characterization of a Full-Scale Wind Turbine through High-Frequency Surface Pressure Measurements

2015 ◽  
Vol 14 (5-6) ◽  
pp. 729-766 ◽  
Author(s):  
Franck Bertagnolio ◽  
Helge Aa. Madsen ◽  
Christian Bak ◽  
Niels Troldborg ◽  
Andreas Fischer
Keyword(s):  
Wind Turbine ◽  
Surface Pressure ◽  
High Frequency ◽  
Full Scale ◽  
Aerodynamic Noise ◽  
Pressure Measurements ◽  
Noise Characterization

scholarly journals Evaluation of Tip Loss Corrections to AD/NS Simulations of Wind Turbine Aerodynamic Performance

2019 ◽  
Vol 9 (22) ◽  
pp. 4919 ◽  
Author(s):  
Wei Zhong ◽  
Tong Guang Wang ◽  
Wei Jun Zhu ◽  
Wen Zhong Shen
Keyword(s):  
Wind Turbine ◽  
Wind Farm ◽  
Relative Difference ◽  
Superior Performance ◽  
Navier Stokes ◽  
Special Focus ◽  
Actuator Disc ◽  
Blade Tip ◽  
Blade Loads ◽  
Blade Element

The Actuator Disc/Navier-Stokes (AD/NS) method has played a significant role in wind farm simulations. It is based on the assumption that the flow is azimuthally uniform in the rotor plane, and thus, requires a tip loss correction to take into account the effect of a finite number of blades. All existing tip loss corrections were originally proposed for the Blade-Element Momentum Theory (BEMT), and their implementations have to be changed when transplanted into the AD/NS method. The special focus of the present study is to investigate the performance of tip loss corrections combined in the AD/NS method. The study is conducted by using an axisymmetric AD/NS solver to simulate the flow past the experimental NREL Phase Ⅵ wind turbine and the virtual NREL 5MW wind turbine. Three different implementations of the widely used Glauert tip loss function F are discussed and evaluated. In addition, a newly developed tip loss correction is applied and compared with the above implementations. For both the small and large rotors under investigation, the three different implementations show a certain degree of difference to each other, although the relative difference in blade loads is generally no more than 4%. Their performance is roughly consistent with the standard Glauert correction employed in the BEMT, but they all tend to make the blade tip loads over-predicted. As an alternative method, the new tip loss correction shows superior performance in various flow conditions. A further investigation into the flow around and behind the rotors indicates that tip loss correction has a significant influence on the velocity development in the wake.

Location of aerodynamic noise sources from a 200 kW vertical-axis wind turbine

2017 ◽  
Vol 400 ◽  
pp. 154-166 ◽  
Author(s):  
Fredric Ottermo ◽  
Erik Möllerström ◽  
Anders Nordborg ◽  
Jonny Hylander ◽  
Hans Bernhoff
Keyword(s):  
Wind Turbine ◽  
Vertical Axis ◽  
Aerodynamic Noise ◽  
Vertical Axis Wind Turbine ◽  
Noise Sources

Prediction of Aerodynamic Noise Radiated From a Vertical-Axis Wind Turbine

2003 ◽  
Author(s):  
Akiyoshi Iida ◽  
Akisato Mizuno ◽  
Kyoji Kamemoto
Keyword(s):  
Flow Field ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Sound Source ◽  
Vertical Axis ◽  
Aerodynamic Performance ◽  
Low Noise ◽  
Aerodynamic Noise ◽  
Speed Ratio ◽  
Vertical Axis Wind Turbine

Unsteady flow field and flow induced noise of vertical axis wind turbine are numerically investigated. The flow field is numerically calculated by the vortex method with core-spreading model. This simulation obtains aerodynamic performance and aerodynamic forces. Aerodynamic noise is also simulated by using Ffowcs Williams-Hawkings equation with compact body and low-Mach number assumptions. Tip speed of rotor blades are not so high, then the contribution of the moving sound source is smaller than that of the dipole sound source. Since the maximum power coefficient of VAWT can be obtained at lower tip-speed ratio compared to the conventional, horizontal axis wind turbines, the aerodynamic noise from vertical axis wind turbine is smaller than that of the conventional wind turbines at the same aerodynamic performance. This result indicates that the vertical axis wind turbines are useful to develop low-noise wind turbines.

Wind Turbine Blade Tip Flow and Noise Prediction by Large-eddy Simulation

2004 ◽  
Vol 126 (4) ◽  
pp. 1017-1024 ◽  
Author(s):  
Oliver Fleig ◽  
Makoto Iida ◽  
Chuichi Arakawa
Keyword(s):  
Large Eddy Simulation ◽  
Wind Turbine ◽  
Turbine Blade ◽  
Acoustic Emissions ◽  
Wind Turbine Blade ◽  
Tip Vortex ◽  
Aerodynamic Noise ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Blade Tip

The purpose of this research is to investigate the physical mechanisms associated with broadband tip vortex noise caused by rotating wind turbines. The flow and acoustic field around a wind turbine blade is simulated using compressible large-eddy simulation and direct noise simulation, with emphasis on the blade tip region. The far field aerodynamic noise is modeled using acoustic analogy. Aerodynamic performance and acoustic emissions are predicted for the actual tip shape and an ogee type tip shape. For the ogee type tip shape the sound pressure level decreases by 5 dB for frequencies above 4 kHz.

Simulation of Wave Impacts at Belwind Offshore Wind Farm and Comparison With Full-Scale Measurements

2017 ◽  
Author(s):  
Tim Bunnik ◽  
Wout Weijtjens ◽  
Christof Devriendt
Keyword(s):  
Numerical Model ◽  
Wind Turbine ◽  
Wind Farm ◽  
Full Scale ◽  
Offshore Wind ◽  
Mode Shapes ◽  
Wave Loads ◽  
Cfd Model ◽  
Offshore Wind Farm ◽  
Wave Radar

The effects of operational wave loads and wind loads on offshore monopile wind turbines are well understood. For most sites, however, the water depth is such that steep and/or breaking waves will occur causing impulsive excitation of the monopile and consequently considerable stresses, displacements and accelerations in the monopile, tower and turbine. At Belwind offshore wind farm (offshore Zeebrugge, Belgium) the waves and accelerations of a Vestas V90 3MW wind turbine have been monitored since November 2013, using wave radar and several accelerometers. During this period the wind turbine was exposed to several storms and experienced several wave impacts, resulting in vibrations in the monopile. The measurements were compared with results from a numerical model for the flexible response of wind turbines due to steep waves. Previously this model was compared with scale model tests with satisfying results. The full-scale measurements provide an additional cross-check of the model. The numerical model consists of a one-way coupling between a CFD model for wave loads and a simplified structural model based on mode shapes. An iterative wave calibration technique has been developed in the CFD model to ensure a good match between the simulated and measured incoming wave profile, obtained with the wave radar. This makes a deterministic comparison between simulations and measurements possible. This iteration is carried out in a 2D CFD domain (assuming long-crested waves) and is therefore relatively cheap. The calibrated numerical wave is then simulated in a 3D CFD domain including a (fixed) wind turbine. The resulting wave pressures on the turbine have been used to compute the modal excitation and subsequently the modal response of the wind turbine. The mode shapes have been estimated from the measured accelerations at the Belwind turbine. A grid refinement study was done to verify the results from the numerical model. The horizontal accelerations resulting from this one-way coupling are in fair agreement with the measured accelerations.

scholarly journals Aeroacoustic Source Separation on a Full Scale Nose Landing Gear Featuring Combinations of Low Noise Technologies

2015 ◽  
Author(s):  
Eleonora Neri ◽  
John Kennedy ◽  
Gareth J. Bennett
Keyword(s):  
Noise Reduction ◽  
Low Noise ◽  
Landing Gear ◽  
Full Scale ◽  
Commercial Aircraft ◽  
Noise Sources ◽  
Gear Noise ◽  
Aircraft Landing ◽  
Total Noise ◽  
Landing Gear Noise

The reduction of noise generated by aircraft at take-off and approach is crucial in the design of new commercial aircraft. Landing gear noise is significant contribution to the total noise sources during approach. The noise is generated by the interaction between the non-aerodynamic components of the landing gear and the flow, which leads to turbulence generated noise. This research presents results from the European Clean Sky funded ALLEGRA project. The project investigated a full-scale Nose Landing Gear (NLG) model featuring the belly fuselage, bay cavity and hydraulic dressing. A number of low noise treatments were applied to the NLG model including a ramp door spoiler, a wheel axel wind shield, wheel hub caps and perforated fairings. Over 250 far field sensors were deployed in a number of microphone arrays. Since technologies were tested both in isolation and in combination the additive effects of the technologies can be assessed. This study describes the different techniques used to quantify the contribution of each technology to the global noise reduction. The noise reduction technologies will be assessed as a function of frequency range and through beamforming techniques such as source deletion.

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